PCI: Read capability list as dwords, not bytes

Reading both the capability ID and "next" pointer at the same time lets us
parse the list with half the number of config reads.
Signed-off-by: NSean O. Stalley <sean.stalley@intel.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

drivers/pci/pci.c

@@ -145,19 +145,22 @@ static int __pci_find_next_cap_ttl(struct pci_bus *bus, unsigned int devfn,
 				   u8 pos, int cap, int *ttl)
 {
 	u8 id;
+	u16 ent;
+
+	pci_bus_read_config_byte(bus, devfn, pos, &pos);
 
 	while ((*ttl)--) {
-		pci_bus_read_config_byte(bus, devfn, pos, &pos);
 		if (pos < 0x40)
 			break;
 		pos &= ~3;
-		pci_bus_read_config_byte(bus, devfn, pos + PCI_CAP_LIST_ID,
-					 &id);
+		pci_bus_read_config_word(bus, devfn, pos, &ent);
+
+		id = ent & 0xff;
 		if (id == 0xff)
 			break;
 		if (id == cap)
 			return pos;
-		pos += PCI_CAP_LIST_NEXT;
+		pos = (ent >> 8);
 	}
 	return 0;
 }